In different individuals exposed to radiation, radiation will cause variable levels of rapid combined tissue death, cell apoptosis and necrosis leading to toxicity. This acute tissue loss correlates with radiation injury. DiaCarta?s RadTox QuantiDNATMdiagnostic product measures tissue loss and is related to radiation dose, field size, known sensitive organ exposure, and use of sensitizers. RadTox QuantiDNATM is a unique, first generation, patented technology that measures acute tissue damage shortly (24 hr) following a first radiation exposure. RadTox QuantiDNATM employs a few microliters of plasma from blood. Moreover, as DiaCarta already has CLIA-ready and CE-marked products on the same platform, regulatory approval would be sought and easily achieved. In this phase I SBIR, DiaCarta proposes to: Objective 1: Develop a CLIA certification-ready test for immediate deployment in clinical studies using our CLIA certified laboratory Objective 2: Evaluate RadTox QuantiDNATM using prospective toxicity data and parallel plasma specimens from prostate cancer patients Assuming positive pilot data we will prepare and submit a Phase II SBIR to conduct a pivotal clinical study and develop additional organ-specific products using RadTox QuantiDNATM.